Lionfish are known to marine aquarists for two main reasons these being their predatory nature and their finnage which is unusual.
There are several lionfish types, probably the most well known one being the common lionfish, Pterois volitans, which is also the one usually most available. This fish can grow to around 12 inches.
The dwarf lionfish is named because of its comparative size, it could grow to around 7 inches. This fish can also usually be obtained without too much trouble. Though the adult size is around 7 inches, the fish is often for sale when much smaller. The link shows some photographs of the fish, some of these demonstrate how the colouration is reasonably effective as camouflage.
Though there seem to always be occasional exceptions, the dwarf lionfish, proper name Dendrochirus brachypterus, is not for a reef aquarium. For a start it is a predator and will eat the smaller fish that are often kept, further it is likely to eat or damage some invertebrates.
In a fish only aquarium the dwarf lionfish should be kept with fish larger than itself because, as said, it will eat smaller ones and even ones more or less its own size – selecting the fish to go in a fish only community needs particular care because, again as said, the ones for sale are often small. Clearly they are going to grow and as they grow the fish population is going to reduce. Even at the initial small size they could eat other small fish. The predatory tendency maybe could be kept at bay or reduced if the fish is fed well, though this isn’t a guarantee.
Some aquarists keep the fish in a species aquarium as unlike tangs it does not require a large swimming space. This isn’t a bad idea as in addition to the community fish in the fish only aquarium being secure, the dwarf lionfish does not usually object to other same type fish being present. Obviously care has to be taken with stocking levels and also care with the fish themselves – one could maybe eat another if it was smaller.
A novice aquarist who wishes to gain some experience with a fish only aquarium could select the dwarf lionfish as a good addition, as the fish is hardy. The word ‘hardy’ does not mean that attention to seawater quality is not important, it is. The meaning is that the fish should withstand some common mistakes a novice could make, one prime example is overfeeding which will bring seawater quality down.
Mentioning the word feeding, this should be reasonably straightforward as the fish is predatory. It used to be said that small goldfish could be used as ‘feeder fish’ as they are inexpensive and last long enough in salt water to attract the attention of the lionfish. Nowadays this is not seen as ethical and is considered cruel. In addition, goldfish naturally live in freshwater, so is this food correct from a dietary point? The best way to feed the lionfish is to obtain frozen marine food such as lance fish, which is readily available. These are fairly small fish and the lionfish should be able to take them, if not they can easily be cut when frozen. Ensure of course that they are completely thawed (don’t thaw in a microwave as this reduces the nutritional value; thaw in some reverse osmosis water or seawater).
Feeding could present one problem and that is the food is of course dead, the lionfish is a predator and used to hunting live food so could ignore that provided. The answer to this is usually successful. Obtain some thin white cotton thread and fasten the food loosely to it. When the food is placed in the aquarium make sure it is in the vicinity of the fish and make it move about gently. Some patience could be required but eventually the hungry fish should take it. The cotton should come off easily. Peter once kept a lionfish in a species aquarium and it learned to take food in this way. In time, as soon as the food appeared at the surface it was taken without any delay. Having mentioned a potential problem with feeding it is possible that there could be no problem at all, it has been reported that the fish very occasionally will take anything meaty floating in the seawater, very small or not. Normal feeding of the lionfish is not required every day; every other day should be tried. The feeding frequency can be determined by observation, the fish should be reasonably eager.
The fish has spines that are venomous, just as much so as the larger lionfish. This needs to be remembered when hands are in the aquarium for maintenance. Also it is possible that a plastic bag could be punctured when the fish is being transported home, the dealer should ensure this is unlikely to cause problems by double or even triple bagging.
Once the dwarf lionfish is in the aquarium, having got there using the correct acclimatization technique, it should settle down quickly. The aquarist then has a fish that is unusual in finnage and different to observe. Though slow moving in comparison to others, it is a counter to the more usually kept fish. Perhaps the ideal is a species aquarium which sits underneath the larger display one?